The property of more than 18 acres is owned by investor Robert Fell and includes an 8,000-square-foot mansion and a 10,000-square-foot horse barn.

An equestrian estate about 7 miles south of Santa Barbara, Calif., is listing for $26.5 million. The property, more than 18 acres, is owned by Robert Fell, an entrepreneur and venture investor who was an avid polo player.

The estate, completed in 2001, includes an approximately 8,000-square-foot, five-bedroom mansion inspired by French and Italian architecture, Mr. Fell said. There is also a guesthouse atop a separate two-car garage, plus a roughly 800-square-foot pool house with a gym and one bedroom apartment. The...